Dithiocarbamates have been known for some time. Examples of various structurally different dithiocarbamates are disclosed in the following patents:
3,407,2225,693,5984,885,3654,125,4795,902,7763,867,3595,686,3974,836,9424,758,3623,509,0512,710,8725,789,3574,927,5525,629,2723,356,7025,840,6644,957,6434,876,3755,759,9654,098,705
Examples of hydroxy-substituted dithiocarbamates are disclosed in the following references and patents: Zh. Org. Khim. (1991), 27(1), 161–170; Zh. Org. Khim. (1988), 24(2), 286–291; Z. Chem. (1987), 27(1), 24–25; Zh. Org. Khim. (1985), 21(6), 1173–1176: Neftekhim (1983), 23(3), 409–412; Neftepererab. Neftekhim. (Moscow) (1983), (1), 20–22; U.S. Pat. No. 3,407,222; and U.S. Pat. No. 3,867,359.
Examples of commercially available dithiocarbamates include Vanlube(R)® 7723, a methylenebis(dibutyldithiocarbamate), Molyvan® A, a molybdenum oxysulfide dithiocarbamate, Molyvan® 822, an organo molybdenum dithiocarbamate, Vanlube® AZ, a zinc diamyldithiocarbamate, Vanlube® 71, a lead diamyldithiocarbamate, Vanlube® 73, an antimony dialkyldithiocarbamate, and Vanlube® 732, a dithiocarbamate derivative, all obtained from R. T. Vanderbilt Company, Inc.
There are many examples in the patent literature showing the use of molybdenum additives as antioxidants, deposit control additives, anti-wear additives and friction modifiers, including:
U.S. Pat. No. 5,840,672U.S. Pat. No. 5,814,587U.S. Pat. No. 4,529,526WO 95/07966U.S. Pat. No. 5,650,381U.S. Pat. No. 4,812,246U.S. Pat. No. 5,458,807WO 95/07964U.S. Pat. No. 5,880,073U.S. Pat. No. 5,658,862U.S. Pat. No. 5,696,065WO 95/07963U.S. Pat. No. 5,665,684U.S. Pat. No. 4,360,438U.S. Pat. No. 5,736,491WO 95/27022U.S. Pat. No. 5,786,307U.S. Pat. No. 4,501,678U.S. Pat. No. 5,688,748EP 0 447 916 A1U.S. Pat. No. 5,807,813U.S. Pat. No. 4,692,256U.S. Pat. No. 5,605,880WO 95/07962U.S. Pat. No. 5,837,657U.S. Pat. No. 4,832,867U.S. Pat. No. 4,705,641EP 0 768 366 A1U.S. Pat. No. 5,925,600U.S. Pat. No. 5,922,654U.S. Pat. No. 5,916,851U.S. Pat. No. 5,895,779U.S. Pat. No. 5,888,945U.S. Pat. No. 5,939,364U.S. Pat. No. 6,074,993U.S. Pat. No. 6,063,741U.S. Pat. No. 6,017,858U.S. Pat. No. 5,994,277U.S. Pat. No. 5,824,627U.S. Pat. No. 5,763,374U.S. Pat. No. 4,995,996U.S. Pat. No. 4,990,271U.S. Pat. No. 4,978,464U.S. Pat. No. 4,846,983U.S. Pat. No. 4,832,857U.S. Pat. No. 4,478,729U.S. Pat. No. 4,466,901U.S. Pat. No. 4,428,848U.S. Pat. No. 4,414,122U.S. Pat. No. 4,402,840U.S. Pat. No. 4,395,343U.S. Pat. No. 4,394,279U.S. Pat. No. 4,369,119U.S. Pat. No. 4,362,633U.S. Pat. No. 4,357,149U.S. Pat. No. 4,324,672U.S. Pat. No. 4,285,822U.S. Pat. No. 4,283,295U.S. Pat. No. 4,272,387U.S. Pat. No. 4,265,773U.S. Pat. No. 4,263,152U.S. Pat. No. 4,261,843U.S. Pat. No. 4,259,195U.S. Pat. No. 4,259,194U.S. Pat. No. 4,248,720U.S. Pat. No. 4,202,781U.S. Pat. No. 4,201,683U.S. Pat. No. 4,192,757U.S. Pat. No. 4,178,258U.S. Pat. No. 4,164,473U.S. Pat. No. 4,098,705U.S. Pat. No. 3,733,345EP 0 874 040 A1EP 0 822 246 A3EP 0 768 366 A1WO 00/08120WO 95/07963 A1WO 95/07964 A1WO 95/07965 A1WO 95/07966 A1WO 95/27022 A1WO 96/19551 A1
Examples showing the use of a combination of molybdenum and other ashless dithiocarbamates are found in U.S. Pat. No. 4,360,438; U.S. Pat. No. 6,017,858; WO 96/37585, and EP 0874040 A1.
Studies have suggested that emissions systems can be deactivated as a result of contamination from compounds derived from the engine oil. Other studies have suggested that emissions system durability may be improved by using lubricants containing high metal/phosphorus ratios. Reducing the level of phosphorus in the engine oils has also been suggested as a means of prolonging the efficiency of the catalytic converter. The phosphorus in engine oils originates primarily from zinc dithiophosphates (ZDDP's), which are used to prevent wear and control oxidation. Over the years ZDDP's have demonstrated reliable anti-wear and antioxidant effectiveness. Most engine builders would not recommend engine oils which contain substantial reductions from today's ZDDP levels without extensive proof in the laboratory and the field that wear protection is acceptable. Commercial engine oils meeting API SJ requirements usually contain approximately 0.10 wt. % phosphorus derived from ZDDP. A substantial reduction in ZDDP's, which may be required for catalytic converter durability, would result in significantly higher engine wear and oil oxidation. To compensate for the use of less ZDDP in engine oils, supplemental wear and oxidation inhibitors are required.